Method and apparatus for producing cross-wound bobbins

ABSTRACT

In a process for producing cross-wound packages in a yarn winding device of a textile machine, the helix angle of the wound-on yarn changes during winding on. The helix angle is a variable chosen in dependence on the diameter of the yarn package. This diameter of the package is in turn calculated on the basis of the length of the yarn already wound on. An arrangement for producing cross-wound packages on a number of yarn winding devices comprises a drive for rotating the cross-wound package. A variable, driveable yarn guide is provided at each yarn winding device for laying a yarn in axial direction of the cross-wound package at a variable helix angle. A common sensor for measuring the package diameter at a number of yarn winding devices is provided, which sensor can be positioned to the yarn winding devices one after another.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a process and an arrangement forproducing cross-wound packages at a yarn winding device of a textilemachine, in which the helix angle of the wound-on yarn changes duringthe winding on process. The arrangement comprises a drive for rotatingthe cross-wound package and also comprises on each yarn winding device avariably driveable yarn guide for laying a yarn to be wound in axialdirection of the cross-wound package at a variable helix angle.

In place of the helix angle, the so-called cross-over angle is oftenalso used. The value of the cross-over angle approximates to double thevalue of the helix angle.

A process and an arrangement of the above mentioned type is prior art inGerman published patent application DE 10342 66 A1. The aim of theinvention disclosed in DE 10342266 A1 is the production of a cross-woundpackage having a hard core and a high density in the inner area and alower in the outer area. The yarn is wound on at the beginning of thepackage build-up at a small helix angle and the helix angle is eithercontinuously increased or increased at short intervals. No details aredisclosed regarding how the amount of the increase is selected, norwhether the increases are variable or not, and if so, how. Thecross-wound package produced according to the process in Germanpublished patent application DE 10342266 A1 has random winding, as theso-called winding ratio constantly changes during the winding process.The winding ratio is defined as the number or revolutions of thecross-wound package during a double lift of the yarn guide over thewidth of the cross-wound package. There is therefore always the riskthat the winding ratio takes on integral values and so-called ribbonwinding zones arise, which have an extremely negative influence on theunwinding behaviour of the cross-wound package. An additional devicemust accordingly be on hand to prevent the occurrence of ribbon windingzones. There are no details provided in the prior art document.

It is an object of the present invention to improve a process and anarrangement for producing cross-wound packages.

The object of the present invention has been achieved in that the helixangle is selected based on the package diameter, and that the packagediameter is calculated based on the length of the yarn already wound on.In the case of the arrangement, the object has been achieved in that acontrol system is provided for calculating the cross-wound packagediameter from the length of the yarn already wound on, said controlsystem being connected to the drive of the yarn guide.

The invention has the advantage that the cross-wound package diameter isknown at any given time. In the known arrangement this could only beachieved up to now in that a sensor was placed at each winding head,which sensor measured the cross-wound package diameter. The presentinvention omits this diameter-measuring sensor at each winding head.

As the cross-wound package diameter is known at any given time, therotational speed of the package and therefore also the actual windingratio at any given time can be calculated with the aid of the also knownrotational speed of the cross-wound package. The cross-wound package isdriven on its periphery via a winding roller and rotates as a result ata circumferential speed which essentially corresponds to the speed ofthe winding roller. The yarn guide for placing the yarn to be wound inaxial direction of the cross-wound package is provided with aspeed-regulating drive, which is regulated by the control system, sothat the speed of the yarn guide is also known. As a result the windingratio is computable in the control system so that the winding ratio isknown at any given time during the production of a cross-wound package.

The known cross-wound package diameter permits the controlled winding-onof the yarn constantly at the most optimal helix angle. Cross-woundpackages can be produced which can be adapted to subsequent processingstages. Good unwinding properties of the cross-wound package can beachieved for example with a relatively large helix angle at a smallcross-wound package diameter, and helix angles decreasing with thecross-wound package diameter. Cross-wound packages with a high density,which are particularly suitable for further processing in weaving mills,or dye packages having a particularly homogenous package form, can beproduced selectively.

In the production of cross-wound packages with random winding, thewinding on of the yarn with undesirable winding ratios which lead toribbon winding zones, can be effectively prevented, as the windingratios can be adapted shortly before the occurrence of a non-desirablevalue by means of a variation of the helix angle by changing the yarnguiding speed.

It is in addition possible to produce cross-wound packages withstep-by-step precision winding, in which the winding ratio is keptconstant over a range of diameter areas.

The present invention is particularly suitable for spinning machines, inwhich the yarn is delivered at a known delivery speed which is usuallyconstant. The length of the wound-on yarn is determinable by the controlsystem directly from the known delivery speed. In order that the yarn iswound on at a constant tension at a constant delivery speed, it isnecessary that in the case of a change in traverse speed of the yarnguide in order to change the helix angle, the circumferential speed ofthe winding roller simultaneously changes inversely to the change inspeed of the yarn guide, so that the resulting winding-on speed remainsconstant. As the cross-wound package diameter is known from the controlsystem, it can be provided that the yarn tension is optimized in certaindiameter areas of the cross-wound package. For example it can beadvantageous to wind the yarn on at a somewhat higher level of tensionin the lower diameter area in order to improve the stability of thecross-wound package.

The present invention can also be applied just as well to windingmachines. The length of the yarn already wound on can be calculated atthe winding machine from the winding-on speed, which results from theaddition of the vectors of the circumferential speed and the traversespeed. The yarn tension can be regulated at the winding machine by meansof a yarn brake, so that in the case of a change in the traverse speedfor changing the helix angle, a simultaneous adaptation of thecircumferential speed of the winding roller is not absolutely necessary.

In order to increase the exactness in specifying the length of thewound-on yarn it can be advantageous to gauge the speed of the wound-onyarn directly. The yarn speed can for example be detected by anon-contact speed sensor arranged upstream of the winding head.

The calculation of the cross-wound package diameter with the aid of thelength of the yarn already wound-on can take place in that amathematical model is stored in the control system of the textilemachine or in the winding head's own control system, said mathematicalmodel having been ascertained from preliminary tests. The mathematicalmodel can be stored for a given yarn having specified yarn parameters,such as material, twist and fineness, with known cross-over angles andknown yarn tension, whereby based on the diameter of the tube thecross-wound package diameter can be constantly measured and stored as afunction of the length of the wound-on yarn. With the aid of thismathematical model stored in the control system, the cross-wound packagediameter can be calculated with the aid of the length of the yarnalready wound on at every winding head of the textile machine, withoutany further evaluations of the diameter being necessary. It can beadvantageous that in the calculation of the cross-wound packagediameter, the yarn tension and/or the cross-over angle, at which theyarn is wound on, is taken into consideration. The exactness of themathematical model can be increased when the yarn tension and thecross-over angle can also be taken into consideration as variables.

In a further embodiment of the present invention it can be advantageousthat at specified intervals a reference evaluation of the cross-woundpackage diameter is carried out, in order to correct the calculatedvalue of the cross-wound package diameter. The variables used for thecalculation of the cross-wound package diameter, such as the length ofthe wound-on yarn, are subject to tolerances, so that the calculatedcross-wound package diameter can deviate from the actual value. Theseinaccuracies can be adjusted by means of a reference evaluation of thecross-wound package diameter. The collected data on the actual value ofthe cross-wound package diameter can be used as a new base for furthercalculations of the cross-wound package diameter, so that incorrectvalues arising from tolerances in the measurement of the cross-woundpackage diameter do not reach an unacceptable level. A referencemeasurement of the calculated cross-wound package diameter can becarried out by a common sensor for measuring at a number of windingdevices. The sensor can be positioned to the winding devices one afterthe other and is arranged advantageously on a mobile carriage whichtravels along the textile machine. Only one sensor is necessary for theentire textile machine, so that the configuration of the winding devicewithout its own diameter sensor is still very simple. It can also beadvantageous to adapt and optimize the mathematical model for thecalculation of the cross-wound package diameter with the aid of themeasured values delivered by the sensor. Precision in the formation ofthe cross-wound package in accordance with the desired properties of thecross-wound package, for example good unwinding properties, can herebybe further improved.

The sensor can measure the diameter of the cross-wound package invarious and selectable ways. The sensor, for example, can bepositionable directly to a cross-wound package and can scan the diameterof the cross-wound package in a non-contact manner. The measurement ofthe cross-wound package can also take place indirectly, in that thesensor is positionable to a package cradle for taking-up the tube of thecross-wound package. The cross-wound package diameter can be calculatedby mechanical or optical scans of the position of the package cradleabove the winding roller.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further objects, features and advantages of the presentinvention will become more readily apparent from the following detaileddescription thereof when taken in conjunction with the accompanyingdrawings wherein:

FIG. 1 is a very schematically shown side view of a spinning machine inthe area of a winding head,

FIG. 2 is a frontal view of the spinning machine of FIG. 1 comprising anumber of adjacent winding heads,

FIG. 3 shows velocity vectors.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 depict a very schematic section of a spinning machine. Ayarn produced in a spinning unit 1 is withdrawn by means of a deliveryroller pair 3, 4 out of the spinning unit 1 and fed at a delivery speedto a winding head 5 and wound onto a cross-wound package 6. The spinningunit 1 can be optional, for example an air jet spinning arrangement oran open-end spinning arrangement. The production of a yarn in suchspinning units is known and needs no further explanation. The deliveryroller 3 of the delivery roller pair 3, 4 is driveable by means of adrive 7 and transports the yarn nipped between the delivery rollers 3and 4 at as constant delivery speed v₁ as possible in order to ensure auniform yarn formation. From the delivery roller pair 3, 4, the yarn 2reaches the cross-wound package 6 via a stationary yarn guide 8 and ayarn guide 9 traversing in the direction of the double arrows B. Thecross-wound package 6 comprises a tube 10 and a cylindrical or conicalyarn body 11, which is formed by means of the yarn 2 being wound inlayers onto the tube 10. The tube 10 has a hinged support in a packagecradle 12 and the cross-wound package 6 lies with its outer peripheralsurface on a winding roller 13. The package cradle 12 is swivel-mountedon an axle 14 and, if required, loading devices could be arranged to thepackage cradle 12 (in a way not shown), said loading devices increasingthe pressure of the cross-wound package 6 to the winding roller 13. Thewinding roller 13 is driven to rotate by a drive 15. The cross-woundpackage 6 rotates at a circumferential speed v₂ of the winding roller13. As the cross-wound package diameter D of the cross-wound packageincreases with the amount of wound on yarn 2, the speed of thecross-wound package 6 changes at the given speed v₂.

The yarn guide 9 traversing in direction B serves to place the yarn 2 tobe wound in axial direction of the cross-wound package, while thecross-wound package 6 is driven to rotate by the winding roller 13. Theyarn 2 is wound in a helical curve shape at a helical angle α onto thecross-wound package 6. The yarn guide 9 moves at a traversing speed v₃,which when changed also renders the helix angle α changeable. Theaddition of the vectors of the circumferential speed v₂ and thetraversing speed v₃, which are perpendicular to one another, results inthe winding speed v₄, at which winding speed v₄ the yarn 2 runs onto thecross-wound package 6.

The yarn guide 9 is depicted in this shown example in the form of a ringapplied to a pivot lever 16, which yarn guide 9 can move axially to andfrom to the cross-wound package in traversing direction B by means ofthe drive 17 which is connected to the pivot lever 16. The embodiment ofthe yarn guide 9 and its drive are just simply examples and can just aswell have different designs. For example the yarn guide 9 can also betwo impeller wheels rotating in opposite directions, which set the yarnin traverse motion.

The drive 17 of the yarn guide 9 and the drive 15 of the winding roller13 are connected to a control system 18. The control system 18 controlsthe drives 15 and 17 in such a way that the desired circumferentialspeed v₂ and the traversing speed v₃ are given. The control system 18 isalso connected to the drive 7 of the delivery roller pair 3, 4. When thecontrol system 18 does not control the drive 7, it receives at leastinformation on the delivery speed v₁ of the delivery roller 3, 4.

At a constant delivery speed v₁, it is important that also the windingspeed v₄ remains essentially constant. The winding speed v₄ can varyslightly from the delivery sped v₁ in order to ensure a specific yarntension of the yarn 2. With the aid of the control system 18, thecircumferential speed v₂ and the traversing speed v₃ can be socontrolled that the helix angle α is changeable while the winding speedv4 remains constant thereby. An example is shown in FIG. 3 in which thehelix angle α is to be increased to a larger helix angle α′. For thispurpose, the circumferential speed v₂ is reduced to the value v′₂ andthe traversing speed v₃ is increased to the value v′₃.

In accordance with the present invention it is provided that the helixangle α is selected based on the cross-wound package diameter D, inorder to produce a cross-wound package 6 with specified properties. Thecross-wound package diameter D is calculated on the basis of the lengthof yarn 2 already wound on. For this purpose a mathematical model isstored in the control system 18, with which the cross-wound packagediameter D is calculable on the basis of the length of yarn 2 alreadywound on.

To increase accuracy, a common sensor 19 is provided on a number ofwinding heads 5 for measuring the cross-wound package diameter D. As canbe seen in FIG. 2, a number of spinning units 1 and the respectivewinding heads 5 are arranged adjacently to one another in the spinningmachine. Standard spinning machines comprise several hundred spinningunits 1 adjacent to one another, each of which produces a yarn 2simultaneously. A mobile unit 20 is arranged to the spinning machine andis movable in longitudinal direction of the spinning machine, whichmobile unit 20 can be positioned to individual winding heads 5 or to thespinning units 1. The mobile unit 20 can, for example, be a maintenancedevice, which serves to repair end breaks in the spinning unit 1 and/orto replace a full cross-wound package 6 with an empty tube 10. Thesensor 19 is arranged on the maintenance device 20. The sensor 19measures the diameter D of the cross-wound package 6 at that windinghead 5 past which the maintenance device 20 has just moved. The sensor19 can hereby, for example, as denoted by the broken-lined arrow 21,read the surface of the yarn body 11 directly and thus calculate thecross-wound package diameter D.

Alternatively it can be provided that the sensor 19 determines thecross-wound package diameter D when the maintenance device 20 stops at aspinning unit in order to repair an end break.

It can be advantageous that, for example, the sensor 19 scans theposition of the package cradle 12, as denoted by the broken-lined arrow22. The reading of the position of the package cradle 12 is an indirectmeasurement for the cross-wound package diameter D. The measuring of thepackage cradle 12 can, for example, take place either mechanically bymeans of a lever or also in an optical, non-contact way.

Due to the controlled measurements at specified intervals of thecross-wound package diameter D by the sensor 19, determined values ofthe cross-wound package diameter D can be corrected in the controlsystem 18. The diameter values collected by the reference measurement atone winding head can be used as the basis for further calculations ofthe cross-wound package diameter, so that the calculated value issignificantly more accurate. It can also be provided that by means ofeach measured cross-wound package diameter D, the mathematical modelstored in the control system 18 can be improved and optimized for thecalculation of the cross-wound package diameter D. In so doing, theaccuracy of the diameter calculations at all winding heads 5 areimproved. With the application of the present invention, cross-woundpackages 6 having exactly defined properties can be produced very simplyand cost-effectively for further processing, without a sensor 19 forcontinuous scanning of the cross-wound package diameter D being presentat each individual winding head 5.

1. A process for producing cross-wound packages at a winding head of atextile machine, whereby the helix angle of the wound on yarn changesduring winding on, characterized in that the helix angle is selected independence on the cross-wound package diameter, and in that thecross-wound package diameter is calculated on the basis of the length ofthe yarn already wound on.
 2. A process according to claim 1, wherein inthe calculation of the cross-wound package diameter, the yarn tensionand/or the helix angle, with which the yarn was wound on, is taken intoconsideration.
 3. A process according claim 1, wherein a referencemeasurement of the cross-wound package diameter is carried out, in orderto correct the calculated value of the cross-wound package diameter. 4.An arrangement for producing cross-wound packages (6) at a number ofwinding heads (5) of a textile machine comprising a drive (13) forrotating the cross-wound package (6) and also comprising at each windinghead (5) a variably driveable yarn guide (9) for placing a yarn (2) tobe wound on in axial direction of the cross-wound package (6) at avariable helix angle (α), wherein a control system (18) for calculatingthe cross-wound package diameter (D) on the basis of the amount of yarn(2) already wound on is provided, said control system (18) beingconnected to the drive (17) of the yarn guide (9).
 5. An arrangementaccording to claim 4, wherein a common sensor (19) is provided formeasuring the cross-wound package diameter (D) at a number of windingheads (5).
 6. An arrangement according to claim 4, wherein the sensor(19) is positionable to the winding heads (5) one after another.
 7. Anarrangement according to claim 4, wherein the sensor (19) is arranged ona travelling carriage (20) which is driven along the length of thetextile machine.
 8. An arrangement according to claim 4, wherein thesensor (19) is positionable directly to a cross-wound package.
 9. Anarrangement according to claim 4, wherein the sensor (19) ispositionable to a package cradle (12) for taking up a tube (10) of thecross-wound package (6).